SummaryThis proposal aims to unravel mysteries at the frontier of number theory and other areas of mathematics and physics. The main focus will be to understand and exploit “modularity” of q-hypergeometric series. “Modular forms are functions on the complex plane that are inordinately symmetric.” (Mazur) The motivation comes from the wide-reaching applications of modularity in combinatorics, percolation, Lie theory, and physics (black holes).
The interplay between automorphic forms, q-series, and other areas of mathematics and physics is often two-sided. On the one hand, the other areas provide interesting examples of automorphic objects and predict their behavior. Sometimes these even motivate new classes of automorphic objects which have not been previously studied. On the other hand, knowing that certain generating functions are modular gives one access to deep theoretical tools to prove results in other areas. “Mathematics is a language, and we need that language to understand the physics of our universe.”(Ooguri) Understanding this interplay has attracted attention of researchers from a variety of areas. However, proofs of modularity of q-hypergeometric series currently fall far short of a comprehensive theory to describe the interplay between them and automorphic forms. A recent conjecture of W. Nahm relates the modularity of such series to K-theory. In this proposal I aim to fill this gap and provide a better understanding of this interplay by building a general structural framework enveloping these q-series. For this I will employ new kinds of automorphic objects and embed the functions of interest into bigger families
A successful outcome of the proposed research will open further horizons and also answer open questions, even those in other areas which were not addressed in this proposal; for example the new theory could be applied to better understand Donaldson invariants.

This proposal aims to unravel mysteries at the frontier of number theory and other areas of mathematics and physics. The main focus will be to understand and exploit “modularity” of q-hypergeometric series. “Modular forms are functions on the complex plane that are inordinately symmetric.” (Mazur) The motivation comes from the wide-reaching applications of modularity in combinatorics, percolation, Lie theory, and physics (black holes).
The interplay between automorphic forms, q-series, and other areas of mathematics and physics is often two-sided. On the one hand, the other areas provide interesting examples of automorphic objects and predict their behavior. Sometimes these even motivate new classes of automorphic objects which have not been previously studied. On the other hand, knowing that certain generating functions are modular gives one access to deep theoretical tools to prove results in other areas. “Mathematics is a language, and we need that language to understand the physics of our universe.”(Ooguri) Understanding this interplay has attracted attention of researchers from a variety of areas. However, proofs of modularity of q-hypergeometric series currently fall far short of a comprehensive theory to describe the interplay between them and automorphic forms. A recent conjecture of W. Nahm relates the modularity of such series to K-theory. In this proposal I aim to fill this gap and provide a better understanding of this interplay by building a general structural framework enveloping these q-series. For this I will employ new kinds of automorphic objects and embed the functions of interest into bigger families
A successful outcome of the proposed research will open further horizons and also answer open questions, even those in other areas which were not addressed in this proposal; for example the new theory could be applied to better understand Donaldson invariants.

Max ERC Funding

1 240 500 €

Duration

Start date: 2014-01-01, End date: 2019-04-30

Project acronymCHAPARDYN

ProjectChaos in Parabolic Dynamics: Mixing, Rigidity, Spectra

Researcher (PI)Corinna Ulcigrai

Host Institution (HI)UNIVERSITY OF BRISTOL

Call DetailsStarting Grant (StG), PE1, ERC-2013-StG

Summary"The theme of the proposal is the mathematical investigation of chaos (in particular ergodic and spectral properties) in parabolic dynamics, via analytic, geometric and probabilistic techniques. Parabolic dynamical systems are mathematical models of the many phenomena which display a ""slow"" form of chaotic evolution, in the sense that nearby trajectories diverge polynomially in time. In contrast with the hyperbolic case and with the elliptic case, there is no general theory which describes parabolic dynamical systems. Only few classical examples are well understood.
The research plan aims at bridging this gap, by studying new classes of parabolic systems and unexplored properties of classical ones. More precisely, I propose to study parabolic flows beyond the algebraic set-up and infinite measure-preserving parabolic systems, both of which are very virgin fields of research, and to attack open conjectures and questions on fine chaotic properties, such as spectra and rigidity, for area-preserving flows. Moreover, connections between parabolic dynamics and respectively number theory, mathematical physics and probability will be explored. g New techniques, stemming from some recent breakthroughs in Teichmueller dynamics, spectral theory and infinite ergodic theory, will be developed.
The proposed research will bring our knowledge significantly beyond the current state-of-the art, both in breadth and depth and will identify common features and mechanisms for chaos in parabolic systems. Understanding similar features and common geometric mechanisms responsible for mixing, rigidity and spectral properties of parabolic systems will provide important insight towards an universal theory of parabolic dynamics."

"The theme of the proposal is the mathematical investigation of chaos (in particular ergodic and spectral properties) in parabolic dynamics, via analytic, geometric and probabilistic techniques. Parabolic dynamical systems are mathematical models of the many phenomena which display a ""slow"" form of chaotic evolution, in the sense that nearby trajectories diverge polynomially in time. In contrast with the hyperbolic case and with the elliptic case, there is no general theory which describes parabolic dynamical systems. Only few classical examples are well understood.
The research plan aims at bridging this gap, by studying new classes of parabolic systems and unexplored properties of classical ones. More precisely, I propose to study parabolic flows beyond the algebraic set-up and infinite measure-preserving parabolic systems, both of which are very virgin fields of research, and to attack open conjectures and questions on fine chaotic properties, such as spectra and rigidity, for area-preserving flows. Moreover, connections between parabolic dynamics and respectively number theory, mathematical physics and probability will be explored. g New techniques, stemming from some recent breakthroughs in Teichmueller dynamics, spectral theory and infinite ergodic theory, will be developed.
The proposed research will bring our knowledge significantly beyond the current state-of-the art, both in breadth and depth and will identify common features and mechanisms for chaos in parabolic systems. Understanding similar features and common geometric mechanisms responsible for mixing, rigidity and spectral properties of parabolic systems will provide important insight towards an universal theory of parabolic dynamics."

Max ERC Funding

1 193 534 €

Duration

Start date: 2014-01-01, End date: 2019-08-31

Project acronymCOMPASP

ProjectComplex analysis and statistical physics

Researcher (PI)Stanislav Smirnov

Host Institution (HI)UNIVERSITE DE GENEVE

Call DetailsAdvanced Grant (AdG), PE1, ERC-2013-ADG

Summary"The goal of this project is to achieve breakthroughs in a few fundamental questions in 2D statistical physics, using techniques from complex analysis, probability, dynamical systems, geometric measure theory and theoretical physics.
Over the last decade, we significantly expanded our understanding of 2D lattice models of statistical physics, their conformally invariant scaling limits and related random geometries. However, there seem to be serious obstacles, preventing further development and requiring novel ideas. We plan to attack those, in particular we intend to:
(A) Describe new scaling limits by Schramm’s SLE curves and their generalizations,
(B) Study discrete complex structures and use them to describe more 2D models,
(C) Describe the scaling limits of random planar graphs by the Liouville Quantum Gravity,
(D) Understand universality and lay framework for the Renormalization Group Formalism,
(E) Go beyond the current setup of spin models and SLEs.
These problems are known to be very difficult, but fundamental questions, which have the potential to lead to significant breakthroughs in our understanding of phase transitions, allowing for further progresses. In resolving them, we plan to exploit interactions of different subjects, and recent advances are encouraging."

"The goal of this project is to achieve breakthroughs in a few fundamental questions in 2D statistical physics, using techniques from complex analysis, probability, dynamical systems, geometric measure theory and theoretical physics.
Over the last decade, we significantly expanded our understanding of 2D lattice models of statistical physics, their conformally invariant scaling limits and related random geometries. However, there seem to be serious obstacles, preventing further development and requiring novel ideas. We plan to attack those, in particular we intend to:
(A) Describe new scaling limits by Schramm’s SLE curves and their generalizations,
(B) Study discrete complex structures and use them to describe more 2D models,
(C) Describe the scaling limits of random planar graphs by the Liouville Quantum Gravity,
(D) Understand universality and lay framework for the Renormalization Group Formalism,
(E) Go beyond the current setup of spin models and SLEs.
These problems are known to be very difficult, but fundamental questions, which have the potential to lead to significant breakthroughs in our understanding of phase transitions, allowing for further progresses. In resolving them, we plan to exploit interactions of different subjects, and recent advances are encouraging."

Max ERC Funding

1 995 900 €

Duration

Start date: 2014-01-01, End date: 2018-12-31

Project acronymCritical

ProjectBehaviour near criticality

Researcher (PI)Martin Hairer

Host Institution (HI)THE UNIVERSITY OF WARWICK

Call DetailsConsolidator Grant (CoG), PE1, ERC-2013-CoG

Summary"One of the main challenges of modern mathematical physics is to understand the behaviour of systems at or near criticality. In a number of cases, one can argue heuristically that this behaviour should be described by a nonlinear stochastic partial differential equation. Some examples of systems of interest are models of phase coexistence near the critical temperature, one-dimensional interface growth models, and models of absorption of a diffusing particle by random impurities. Unfortunately, the equations arising in all of these contexts are mathematically ill-posed. This is to the extent that they defeat not only ""standard"" stochastic PDE techniques (as developed by Da Prato / Zabczyk / Röckner / Walsh / Krylov / etc), but also more recent approaches based on Wick renormalisation of nonlinearities (Da Prato / Debussche / etc).
Over the past year or so, I have been developing a theory of regularity structures that allows to give a rigorous mathematical interpretation to such equations, which therefore allows to build the mathematical objects conjectured to describe the abovementioned systems near criticality. The aim of the proposal is to study the convergence of a variety of concrete microscopic models to these limiting objects. The main fundamental mathematical tools to be developed in this endeavour are a discrete analogue to the theory of regularity structures, as well as a number of nonlinear invariance principles.
If successful, the project will yield unique insight in the large-scale behaviour of a number of physically relevant systems in regimes where both nonlinear effects and random fluctuations compete with equal strength."

"One of the main challenges of modern mathematical physics is to understand the behaviour of systems at or near criticality. In a number of cases, one can argue heuristically that this behaviour should be described by a nonlinear stochastic partial differential equation. Some examples of systems of interest are models of phase coexistence near the critical temperature, one-dimensional interface growth models, and models of absorption of a diffusing particle by random impurities. Unfortunately, the equations arising in all of these contexts are mathematically ill-posed. This is to the extent that they defeat not only ""standard"" stochastic PDE techniques (as developed by Da Prato / Zabczyk / Röckner / Walsh / Krylov / etc), but also more recent approaches based on Wick renormalisation of nonlinearities (Da Prato / Debussche / etc).
Over the past year or so, I have been developing a theory of regularity structures that allows to give a rigorous mathematical interpretation to such equations, which therefore allows to build the mathematical objects conjectured to describe the abovementioned systems near criticality. The aim of the proposal is to study the convergence of a variety of concrete microscopic models to these limiting objects. The main fundamental mathematical tools to be developed in this endeavour are a discrete analogue to the theory of regularity structures, as well as a number of nonlinear invariance principles.
If successful, the project will yield unique insight in the large-scale behaviour of a number of physically relevant systems in regimes where both nonlinear effects and random fluctuations compete with equal strength."

Max ERC Funding

1 526 234 €

Duration

Start date: 2014-09-01, End date: 2019-08-31

Project acronymGEOMETRICSTRUCTURES

ProjectDeformation Spaces of Geometric Structures

Researcher (PI)Anna Wienhard

Host Institution (HI)RUPRECHT-KARLS-UNIVERSITAET HEIDELBERG

Call DetailsConsolidator Grant (CoG), PE1, ERC-2013-CoG

Summary"Moduli spaces of flat bundles and representation varieties play a prominent role in various areas of mathematics. Historically such spaces first arose in the study of systems of analytic differential equations. Closely related, and in fact locally homeomorphic, are deformation spaces of locally homogeneous geometric structures. Such deformation spaces often arise as solutions to basic geometric problems, and their global properties provide powerful topological invariants, in particular for three- and four-dimensional manifolds.
Due to the ubiquity of these spaces, methods and viewpoints from various areas of mathematics such as dynamical systems, algebraic geometry, gauge theory, representation theory, partial differential equations, number theory and complex analysis can be combined, and their interplay gives rise to the richness of this subject. In recent year there has also been an increasing interaction with theoretical physics, which has been fruitful for both sides.
In recent years the deformation theory of geometric structures has received revived attention due to new developments, which involve in a deeper way the connections to Lie theory and gauge theory. Unexpectedly, many new examples of deformation spaces of geometric structures appeared. Two such developments are Higher Teichmueller theory and Anosov representations of hyperbolic groups, which generalize classical Teichmueller theory and the theory of quasi-Fuchsian representations to the context of Lie groups of higher rank.
The goal of the proposal is to understand the fine structure and internal geometry of deformation spaces of geometric structures, and to further develop the structure theory of discrete subgroups in higher rank Lie groups. Of particular interest are deformation spaces with appear in the connection with higher Teichmueller theory, because they are expected to be of similar mathematical significance as classical Teichmueller space."

"Moduli spaces of flat bundles and representation varieties play a prominent role in various areas of mathematics. Historically such spaces first arose in the study of systems of analytic differential equations. Closely related, and in fact locally homeomorphic, are deformation spaces of locally homogeneous geometric structures. Such deformation spaces often arise as solutions to basic geometric problems, and their global properties provide powerful topological invariants, in particular for three- and four-dimensional manifolds.
Due to the ubiquity of these spaces, methods and viewpoints from various areas of mathematics such as dynamical systems, algebraic geometry, gauge theory, representation theory, partial differential equations, number theory and complex analysis can be combined, and their interplay gives rise to the richness of this subject. In recent year there has also been an increasing interaction with theoretical physics, which has been fruitful for both sides.
In recent years the deformation theory of geometric structures has received revived attention due to new developments, which involve in a deeper way the connections to Lie theory and gauge theory. Unexpectedly, many new examples of deformation spaces of geometric structures appeared. Two such developments are Higher Teichmueller theory and Anosov representations of hyperbolic groups, which generalize classical Teichmueller theory and the theory of quasi-Fuchsian representations to the context of Lie groups of higher rank.
The goal of the proposal is to understand the fine structure and internal geometry of deformation spaces of geometric structures, and to further develop the structure theory of discrete subgroups in higher rank Lie groups. Of particular interest are deformation spaces with appear in the connection with higher Teichmueller theory, because they are expected to be of similar mathematical significance as classical Teichmueller space."

Max ERC Funding

1 570 327 €

Duration

Start date: 2014-01-01, End date: 2018-12-31

Project acronymGETEMO

ProjectGeometry, Groups and Model Theory

Researcher (PI)Emmanuel, François, Jean Breuillard

Host Institution (HI)WESTFAELISCHE WILHELMS-UNIVERSITAET MUENSTER

Call DetailsConsolidator Grant (CoG), PE1, ERC-2013-CoG

SummaryOur proposed research lies at the interface of Geometry, Group Theory, Number Theory and Combinatorics. In recent years, striking results were obtained in those disciplines with the help of a surprise newcomer at the border between mathematics and logic: Model Theory. Bringing its unique point of view and its powerful formalism, Model Theory made a resounding entry into several different fields of mathematics. Here shedding new light on a classical phenomenon, there solving a long-standing open problem via a completely new method.
Recent examples of concrete mathematical problems where Model Theory interacted in a fruitful manner abound: the local version of Hilbert's 5th problem by Goldbring and van den Dries, Szemeredi's theorems in combinatorics and graph theory, the André-Oort conjecture in diophantine geometry (Pila, Wilkie, Zannier), etc. In this vein, and building on Hrushovski's model-theoretic work, Green, Tao and myself recently settled a conjecture of Lindenstrauss pertaining to the structure of approximate groups.
Our plan in this project is to put these methods into further use, to collaborate with model theorists, and to start looking through this prism at a small collection of familiar problems coming from combinatorics, group theory, analysis and spectral geometry of metric spaces, or from arithmetic geometry. Among them: extend our study of approximate groups to the general setting of locally compact groups, obtain uniform estimates on the spectrum of Cayley graphs of large finite groups, prove an analogue for character varieties of the Pink-Zilber conjectures in relation with rigidity theory for discrete subgroups of Lie groups, and clarify the links between uniform spectral gaps and height lower bounds in diophantine geometry with a view towards Lehmer's conjecture.

Our proposed research lies at the interface of Geometry, Group Theory, Number Theory and Combinatorics. In recent years, striking results were obtained in those disciplines with the help of a surprise newcomer at the border between mathematics and logic: Model Theory. Bringing its unique point of view and its powerful formalism, Model Theory made a resounding entry into several different fields of mathematics. Here shedding new light on a classical phenomenon, there solving a long-standing open problem via a completely new method.
Recent examples of concrete mathematical problems where Model Theory interacted in a fruitful manner abound: the local version of Hilbert's 5th problem by Goldbring and van den Dries, Szemeredi's theorems in combinatorics and graph theory, the André-Oort conjecture in diophantine geometry (Pila, Wilkie, Zannier), etc. In this vein, and building on Hrushovski's model-theoretic work, Green, Tao and myself recently settled a conjecture of Lindenstrauss pertaining to the structure of approximate groups.
Our plan in this project is to put these methods into further use, to collaborate with model theorists, and to start looking through this prism at a small collection of familiar problems coming from combinatorics, group theory, analysis and spectral geometry of metric spaces, or from arithmetic geometry. Among them: extend our study of approximate groups to the general setting of locally compact groups, obtain uniform estimates on the spectrum of Cayley graphs of large finite groups, prove an analogue for character varieties of the Pink-Zilber conjectures in relation with rigidity theory for discrete subgroups of Lie groups, and clarify the links between uniform spectral gaps and height lower bounds in diophantine geometry with a view towards Lehmer's conjecture.

SummaryThe origin of Harmonic Analysis goes back to the study of the heat diffusion, modeled by a differential equation, and the claim made by Fourier that every periodic function can be represented as a series of sines and cosines. In this statement we can find the motivation to many of the advances that have been made in this field. Partial Differential Equations model many phenomena from the natural, economic and social sciences. Existence, uniqueness, convergence to the boundary data, regularity of solutions, a priori estimates, etc., can be studied for a given PDE. Often, Harmonic Analysis plays an important role in such problems and, when the scenarios are not very friendly, Harmonic Analysis turns out to be fundamental. Not very friendly scenarios are those where one lacks of smoothness either in the coefficients of the PDE and/or in the domains where the PDE is solved. Some of these problems lead to obtain the boundedness of certain singular integral operators and this drives one to the classical and modern Calderón-Zygmund theory, the paradigm of Harmonic Analysis. When studying the behavior of the solutions of the given PDE near the boundary, one needs to understand the geometrical features of the domains and then Geometric Measure Theory jumps into the picture.
This ambitious project lies between the interface of three areas: Harmonic Analysis, PDE and Geometric Measure theory. It seeks deep results motivated by elliptic PDE using techniques from Harmonic Analysis and Geometric Measure Theory.This project is built upon results obtained by the applicant in these three areas. Some of them are very recent and have gone significantly beyond the state of the art. The methods to be used have been shown to be very robust and therefore they might be useful towards its applicability in other regimes. Crucial to this project is the use of Harmonic Analysis where the applicant has already obtained important contributions.

The origin of Harmonic Analysis goes back to the study of the heat diffusion, modeled by a differential equation, and the claim made by Fourier that every periodic function can be represented as a series of sines and cosines. In this statement we can find the motivation to many of the advances that have been made in this field. Partial Differential Equations model many phenomena from the natural, economic and social sciences. Existence, uniqueness, convergence to the boundary data, regularity of solutions, a priori estimates, etc., can be studied for a given PDE. Often, Harmonic Analysis plays an important role in such problems and, when the scenarios are not very friendly, Harmonic Analysis turns out to be fundamental. Not very friendly scenarios are those where one lacks of smoothness either in the coefficients of the PDE and/or in the domains where the PDE is solved. Some of these problems lead to obtain the boundedness of certain singular integral operators and this drives one to the classical and modern Calderón-Zygmund theory, the paradigm of Harmonic Analysis. When studying the behavior of the solutions of the given PDE near the boundary, one needs to understand the geometrical features of the domains and then Geometric Measure Theory jumps into the picture.
This ambitious project lies between the interface of three areas: Harmonic Analysis, PDE and Geometric Measure theory. It seeks deep results motivated by elliptic PDE using techniques from Harmonic Analysis and Geometric Measure Theory.This project is built upon results obtained by the applicant in these three areas. Some of them are very recent and have gone significantly beyond the state of the art. The methods to be used have been shown to be very robust and therefore they might be useful towards its applicability in other regimes. Crucial to this project is the use of Harmonic Analysis where the applicant has already obtained important contributions.

Summary"The goal of this project is to develop new techniques combining tools from dynamical systems, analysis and differential geometry to study the existence and properties of invariant manifolds arising from solutions to differential equations. These structures are relevant in the study of the qualitative properties of ODE and PDE and appear very naturally in important questions of mathematical physics. This proposal can be divided in three blocks: the study of periodic orbits and related dynamical structures of vector fields which are solutions to the Euler, Navier-Stokes or Magnetohydrodynamics equations (in the spirit of what is called topological fluid mechanics); the analysis of critical points and level sets of functions which are solutions to some elliptic or parabolic problems (e.g.
eigenfunctions of the Laplacian or Green's functions); a very novel approach based on the nodal sets of a PDE to study the limit cycles of planar vector fields. With the introduction by the Principal Investigator, in collaboration with A. Enciso, of totally new techniques to prove the existence of solutions with prescribed invariant sets for a wide range of PDE, it is now possible to approach these apparently unrelated problems using the same strategy: the construction of local solutions with robust invariant sets and the subsequent uniform approximation by global solutions. Our recent proof of a well known conjecture in topological fluid mechanics, which was popularized by the works of Arnold and Moffatt in the 1960's, illustrates the power of this method. In this project, I intend to delve into and extend the pioneering techniques that we have developed to go significantly beyond the state of the art in some long-standing open problems on invariant manifolds posed by Ulam, Arnold and Yau, among others. This project will allow me to establish an internationally recognized research group in this area at the Instituto de Ciencias Matemáticas (ICMAT) in Madrid."

"The goal of this project is to develop new techniques combining tools from dynamical systems, analysis and differential geometry to study the existence and properties of invariant manifolds arising from solutions to differential equations. These structures are relevant in the study of the qualitative properties of ODE and PDE and appear very naturally in important questions of mathematical physics. This proposal can be divided in three blocks: the study of periodic orbits and related dynamical structures of vector fields which are solutions to the Euler, Navier-Stokes or Magnetohydrodynamics equations (in the spirit of what is called topological fluid mechanics); the analysis of critical points and level sets of functions which are solutions to some elliptic or parabolic problems (e.g.
eigenfunctions of the Laplacian or Green's functions); a very novel approach based on the nodal sets of a PDE to study the limit cycles of planar vector fields. With the introduction by the Principal Investigator, in collaboration with A. Enciso, of totally new techniques to prove the existence of solutions with prescribed invariant sets for a wide range of PDE, it is now possible to approach these apparently unrelated problems using the same strategy: the construction of local solutions with robust invariant sets and the subsequent uniform approximation by global solutions. Our recent proof of a well known conjecture in topological fluid mechanics, which was popularized by the works of Arnold and Moffatt in the 1960's, illustrates the power of this method. In this project, I intend to delve into and extend the pioneering techniques that we have developed to go significantly beyond the state of the art in some long-standing open problems on invariant manifolds posed by Ulam, Arnold and Yau, among others. This project will allow me to establish an internationally recognized research group in this area at the Instituto de Ciencias Matemáticas (ICMAT) in Madrid."

Max ERC Funding

1 260 042 €

Duration

Start date: 2014-01-01, End date: 2018-12-31

Project acronymLIFEINVERSE

ProjectVariational Methods for Dynamic Inverse Problems in the Life Sciences

Researcher (PI)Martin Burger

Host Institution (HI)WESTFAELISCHE WILHELMS-UNIVERSITAET MUENSTER

Call DetailsConsolidator Grant (CoG), PE1, ERC-2013-CoG

SummaryThis project will develop novel techniques for solving inverse problems in life sciences, in particular related to dynamic imaging. Major challenges in this area are efficient four- dimensional image reconstruction under low SNR conditions and further the quantification of image series as obtained from molecular imaging or life microscopy techniques. We will tackle both of them in a rather unified framework as inverse problems for time-dependent (systems of) partial differential equations.
In the solution of these inverse problems we will investigate novel approaches for the following aspects specific to the above-mentioned problems in the life sciences:
1. Solution of inverse problems for PDEs in complex time-varying geometries
2. Development of appropriate variational regularization models for dynamic images, including noise and motion models
3. Improved forward and inverse modelling of cellular and intracellular dynamics leading to novel inverse problems for nonlinear partial differential equations
4. Construction and implementation of efficient iterative solution methods for the arising 4D inverse problems and their variational formulation
All tasks will be driven by concrete applications in biology and medicine and their success will be evaluated in applications to real problems and data. This is based on interdisciplinary work related to electrocardiology and developmental biology. The overall development of methods will however be carried out in a flexible and modular way, so that they become accessible for larger problem classes.

This project will develop novel techniques for solving inverse problems in life sciences, in particular related to dynamic imaging. Major challenges in this area are efficient four- dimensional image reconstruction under low SNR conditions and further the quantification of image series as obtained from molecular imaging or life microscopy techniques. We will tackle both of them in a rather unified framework as inverse problems for time-dependent (systems of) partial differential equations.
In the solution of these inverse problems we will investigate novel approaches for the following aspects specific to the above-mentioned problems in the life sciences:
1. Solution of inverse problems for PDEs in complex time-varying geometries
2. Development of appropriate variational regularization models for dynamic images, including noise and motion models
3. Improved forward and inverse modelling of cellular and intracellular dynamics leading to novel inverse problems for nonlinear partial differential equations
4. Construction and implementation of efficient iterative solution methods for the arising 4D inverse problems and their variational formulation
All tasks will be driven by concrete applications in biology and medicine and their success will be evaluated in applications to real problems and data. This is based on interdisciplinary work related to electrocardiology and developmental biology. The overall development of methods will however be carried out in a flexible and modular way, so that they become accessible for larger problem classes.

Max ERC Funding

966 400 €

Duration

Start date: 2014-03-01, End date: 2019-02-28

Project acronymMODFLAT

Project"Moduli of flat connections, planar networks and associators"

Researcher (PI)Anton Alekseev

Host Institution (HI)UNIVERSITE DE GENEVE

Call DetailsAdvanced Grant (AdG), PE1, ERC-2013-ADG

Summary"The project lies at the crossroads between three different topics in Mathematics: moduli spaces of flat connections on surfaces in Differential Geometry and Topology, the Kashiwara-Vergne problem and Drinfeld associators in Lie theory, and combinatorics of planar networks in the theory of Total Positivity.
The time is ripe to establish deep connections between these three theories. The main factors are the recent progress in the Kashiwara-Vergne theory (including the proof of the Kashiwara-Vergne conjecture by Alekseev-Meinrenken), the discovery of a link between the Horn problem on eigenvalues of sums of Hermitian matrices and planar network combinatorics, and intimate links with the Topological Quantum Field Theory shared by the three topics.
The scientific objectives of the project include answering the following questions:
1) To find a universal non-commutative volume formula for moduli of flat connections which would contain the Witten’s volume formula, the Verlinde formula, and the Moore-Nekrasov-Shatashvili formula as particular cases.
2) To show that all solutions of the Kashiwara-Vergne problem come from Drinfeld associators. If the answer is indeed positive, it will have applications to the study of the Gothendieck-Teichmüller Lie algebra grt.
3) To find a Gelfand-Zeiltin type integrable system for the symplectic group Sp(2n). This question is open since 1983.
To achieve these goals, one needs to use a multitude of techniques. Here we single out the ones developed by the author:
- Quasi-symplectic and quasi-Poisson Geometry and the theory of group valued moment maps.
- The linearization method for Poisson-Lie groups relating the additive problem z=x+y and the multiplicative problem Z=XY.
- Free Lie algebra approach to the Kashiwara-Vergne theory, including the non-commutative divergence and Jacobian cocylces.
- Non-abelian topical calculus which establishes a link between the multiplicative problem and combinatorics of planar networks."

"The project lies at the crossroads between three different topics in Mathematics: moduli spaces of flat connections on surfaces in Differential Geometry and Topology, the Kashiwara-Vergne problem and Drinfeld associators in Lie theory, and combinatorics of planar networks in the theory of Total Positivity.
The time is ripe to establish deep connections between these three theories. The main factors are the recent progress in the Kashiwara-Vergne theory (including the proof of the Kashiwara-Vergne conjecture by Alekseev-Meinrenken), the discovery of a link between the Horn problem on eigenvalues of sums of Hermitian matrices and planar network combinatorics, and intimate links with the Topological Quantum Field Theory shared by the three topics.
The scientific objectives of the project include answering the following questions:
1) To find a universal non-commutative volume formula for moduli of flat connections which would contain the Witten’s volume formula, the Verlinde formula, and the Moore-Nekrasov-Shatashvili formula as particular cases.
2) To show that all solutions of the Kashiwara-Vergne problem come from Drinfeld associators. If the answer is indeed positive, it will have applications to the study of the Gothendieck-Teichmüller Lie algebra grt.
3) To find a Gelfand-Zeiltin type integrable system for the symplectic group Sp(2n). This question is open since 1983.
To achieve these goals, one needs to use a multitude of techniques. Here we single out the ones developed by the author:
- Quasi-symplectic and quasi-Poisson Geometry and the theory of group valued moment maps.
- The linearization method for Poisson-Lie groups relating the additive problem z=x+y and the multiplicative problem Z=XY.
- Free Lie algebra approach to the Kashiwara-Vergne theory, including the non-commutative divergence and Jacobian cocylces.
- Non-abelian topical calculus which establishes a link between the multiplicative problem and combinatorics of planar networks."